Nor-QD (Norethindrone) - Description and Clinical Pharmacology

SPL UNCLASSIFIED SECTION

Patients should be counseled that this product does not protect against HIV infection (AIDS) and other sexually transmitted diseases.

DESCRIPTION

Each yellow NOR-QD^® tablet provides a continuous oral contraceptive regimen of 0.35 mg norethindrone daily, and the inactive ingredients include D&C Yellow No. 10, FD&C Yellow No. 6, lactose, magnesium stearate, povidone, and starch.

The chemical name for norethindrone is 17-Hydroxy-19-Nor-17α-pregn-4-en-20-yn-3-one. The structural formula follows:

norethindrone

Therapeutic class = oral contraceptive.

CLINICAL PHARMACOLOGY

1. Mode of Action. NOR-QD^® progestin-only oral contraceptives prevent conception by suppressing ovulation in approximately half of users, thickening the cervical mucus to inhibit sperm penetration, lowering the mid-cycle LH and FSH peaks, slowing the movement of the ovum through the fallopian tubes, and altering the endometrium.

2. Pharmacokinetics. Serum progestin levels peak about two hours after oral administration, followed by rapid distribution and elimination. By 24 hours after drug ingestion, serum levels are near baseline, making efficacy dependent upon rigid adherence to the dosing schedule. There are large variations in serum levels among individual users. Progestin-only administration results in lower steady-state serum progestin levels and a shorter elimination half-life than concomitant administration with estrogens.